Go to the battery network settings and after scrolling down to the Apps list, click Show Activity. Then look for programs running in the background.
10m on screen – 2m background
Here you will see the list of programs running in the background.
In the linked article it says:
After you switch to another app, some apps run for a short period before they are set to a suspended state.
Try closing the applications in the app switch, as they can still run for a short period of time.
To increase battery life, turn on low power when the battery is low. This increases battery life.
To turn it on, go to Settings -> Battery.
To extend the battery life of the iPhone, turn on low power mode. This reduces power consumption until you turn off or charge iPhone to 80%. When Low Power mode is on, certain settings and features such as app updates, downloads of new TV shows, or podcast episodes, email retrieval, and some visual effects such as True Tone may be reduced or disabled.
You can also see the battery health service at battery levels to see if it needs to be replaced